Novel positron annihilation spectrometer and measurement method thereof

Abstract

The embodiment of the invention relates to a novel positron annihilation spectrometer and a measurement method thereof. The novel positron annihilation spectrometer comprises a radioactive source, a collimator, a detector module and an image obtaining and processing unit, wherein the radioactive source generates positive electron, and the collimator is arranged at the front end of the detector module; the detector module comprises a scintillator, an optical module and a streak tube unit; and the image obtaining and processing unit reads space information recorded by the streak tube unit, obtains the position and amplitude information of gamma rays incident to the detector module according to the space information, respectively obtains the position and amplitude information of gamma rays of a start signal and two termination signals, and further obtains the annihilation life information of positron generated by the radioactive source and the energy information of the gamma rays. The positron annihilation spectrometer can realize the coincidence measurement of high momentum resolution and high time resolution positron annihilation information at the same time and is significantly increased on aspects of momentum resolution, time resolution, testing speed and the like.

Description

technical field [0001] The invention relates to the technical field of nuclear applications, in particular to a novel positron annihilation spectrometer and a measuring method thereof. Background technique [0002] Positrons are the antimatter of electrons. As a positively charged probe, they are attracted by negatively charged defects, and can detect point defects in inorganic crystals such as vacancies, vacancy groups, micro-holes and other vacancy defects, as well as dislocations and dislocations. Ring and other line defects, grain boundaries, phase boundaries and other interface defects are particularly sensitive, so it is a sensitive tool for non-destructive detection of microstructural defects, charge density, electron momentum density and other parameters in materials such as metals, semiconductors, high-temperature superconductors, and polymers. It has the advantages of high detection sensitivity, semi-quantitative analysis of defect concentration, and depth distribu...

AI Technical Summary

Problems solved by technology

In the prior art coincident Doppler measurement system, two high-purity germanium semiconductor detectors on the same straight line coincide to measure the Doppler effect of two gamma photons produced by annihilation, which can improve the momentum resolution (full width at half maximum is reduced to The original ) and effectively reduce the background, thereby extracting the momentum information of the electrons in the inner shell of the atom and used for element resolution around the defect. However, due to the poor time resolution of semiconductor detectors, the high time resolution characteristics are lost

[0005] In addition, in the lifetime-momentum correlation spectrum measurement system, two BaF 2 The detectors respectively measure 1.28MeV and 0.511MeV gamma rays as the start and stop signals, and trigger the high-purity germanium detector opposite to the stop signal to record the energy information of the gamma rays opposite to the stop signal (0.511MeV gamma rays), Therefore, the lifetime-momentum correlation spectroscopy measurement system in the prior art can measure the lifetime spectrum and the energy spectrum at the same time, and realize the purpose of studying the separation of different positron annihilation states through the method of time-selective energy spectroscopy. Constraints in the configuration make it impossible to carry out coincident Doppler measurements simultaneously, thus losing the high momentum resolution characteristic of the coincident Doppler technique

Images